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I cut cabs, though not very well.
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Apr 26, 2016 21:12
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Xun posted:The hardest part for me personally is polishing, sometimes I swear the gem is somehow gaslighting me by "unpolishing" itself. Aka it looks nice from one angle but then looks like poo poo from another Claes: Cleavage is usually not too hard to manage. Anything parallel to the cleavage plane itself will be exceptionally hard to polish, so you want to make sure you don't orient it so that it's parallel to one of your facets. That usually doesn't take too much effort, though some newbies might find the nice flats provided by a cleavage plane (particularly in topaz) to be a tempting place to put their stone's table, which will only end in tears.
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Apr 29, 2016 01:13
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Xun posted:Idk, maybe my prof was scaring us but he told us that if you have a facet parallel to the cleavage plane the gem might CLEAVE IN TWAIN!!! A lot of new and well-regarded polishing laps (and lapidary supplies in general) have been coming out of a company called Gearloose. The disposable mylar oxide toppers are relatively easy to use but can round facet edges and don't last terribly long--his products for polishing are mostly chargeable laps to which you can apply oxides or diamond grit, which he also offers in easy-to-smear lipstick-like formulations. I don't facet so my experience with his laps is somewhat limited, but I really like his oxide and diamond sticks for prepolishing and polishing. Diamond polishing is good for almost any stone, but targeted oxides (eg, Ce or Zr oxides for quartz) can yield better results for particular stones.
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Apr 29, 2016 17:07
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From my searching, it looks like there is a desktop and even a handheld XRF unit for assessing metal purity. No doubt it is very, very expensive.
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Jun 21, 2016 07:31
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While blue fluorescence is rated as a flaw by the strict (and artificial) guidelines of the diamond trade, I've always thought of it more as a desperately-needed bit of personality.
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Jun 23, 2016 22:07
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Nice work! The reason you're getting a yellow flash there is that, when mixing colors of light, red+green = yellow. Unintuitive but they work a bit different from mixing pigments.
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Jul 21, 2016 17:23
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pogothemonkey0 posted:I really like all the beautiful precious stones posted here but I feel like they're out of my style and price range.
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Aug 29, 2016 16:32
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pogothemonkey0 posted:That's not a bad idea. What constitutes "on the cheap," by the way? I have zero frame of reference for the cost of jewelry. (Plus, if you want to take it further, cabochon rough is much, much easier to find than facet rough, and cabochon cutting is much cheaper even for good work. So you can pick out the rough and have it cut just the way you want. I know a guy who does a great job at it, and there may well be local cutters in your area. Cabbing is a lot more casual than faceting in general so there are plenty of people who do it on the side). Scarodactyl fucked around with this message at 20:44 on Sep 2, 2016 |
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Sep 2, 2016 20:37
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I believe the synthetic diamond market has been kept artificially high. I'm not sure how long that will last but for now they're still darned expensive. (Do you think said wearer might go for a colored stone instead? There are more deals to be had and the overall uniqueness and value are going to be higher if you get something like a sapphire instead. But none of that matters if said wearer doesn't want one.)
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Sep 2, 2016 20:50
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This is relevant to pretty much nothing, but I just picked up a piece of pink limb cast chalcedony at a gem show this weekend, slabbed it up and cut a cab from it. I rather like this material, glad I've got plenty of rough now:
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Sep 6, 2016 20:28
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I don't know much about this style of jewelry, but wouldn't something like jade or even chrysoprase provide a nice green color with superior toughness? I suppose that fabrication could be a bit complicated though.
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Oct 14, 2016 19:16
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A nice peach-colored sapphire might be harder to get for sub-arm/leg pricing thanks to the highly in-demand nature of padparascha (which seems to suck in anything orange/pink even if it's not quite there), plus the concern of unknowingly ending up with a Be-treated stone if you do get a 'deal'. There are some good deals to be had with peachy morganite, though you'd want to be sure to shell out for a precision cut stone.
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Oct 27, 2016 06:42
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It is completely stable (the Be is diffused into the stone over about a month at very high temperatures, so it's not going anywhere), and the colors of the stones can be really remarkable. It's not exactly my favorite treatment since it's a lot like dyeing on a conceptual level, but I pick them up when I see them inexpensively priced because the color range is so darned attractive. OK, something unrelated. I was at a local gem show, and came across a guy with buckets of fist-sized nodules of some green-blue material. He was calling it "Brazilian turquoise", but in spite of a slight resemblance it was pretty obvious that it wasn't turquoise of any kind. But it was clearly something natural with a nice color, so I picked up a few pieces for kicks. In the rough:  It's very soft, a bit porous and fractury, and alas greener on the inside than the outside. The powder is also smeary and slippery, a strong hint that it was a sheet silicate and probably a clay mineral. But a few bits of slabs held together well enough to cut cabochons, which I figured were worth setting as a novelty. One of the bluer ones (you can still see pits and such in it, had to work with the realities of the material:  I sent it off to a friend with a gemmoraman for analysis, but she didn't get a hit off of it. She thought it might be metavariscite, which sounded nice enough, but I wasn't sure about that at all. So today I finally schlepped down to my undergrad university and borrowed the x-ray diffractometer.   Welp. (To be fair, one of China's treasured stones for carving seals is made of dickite. But I bet it sounds a lot better in Chinese). Scarodactyl fucked around with this message at 03:18 on Oct 28, 2016 |
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Oct 28, 2016 02:40
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 This is probably more what you're after, though, in terms of quality. They can be downright enchanting, with a really attractive glow. They range all the way from yellow to a weird red (different enough from a typical ruby that they are usually sold as 'red sapphire') with all sorts of oranges, peaches, pinks and orange-pinks in between.
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Oct 28, 2016 20:45
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Brennanite posted:What's a good ballpark for a pair of sapphire stud earrings, 1/2 carat total weight? I'm seeing anything from $30 to $500 online. I assume the stuff at the extreme lower end is junk, but about what price am I going to start seeing standard-level craftsmanship? This depends on a lot of factors--color and treatment (and even origin) of the sapphires is a big one though. Cornflower blue Yogo sapphires are going to cost you a lot more than dark green Australian ones, for instance. Overseas cutting for small sapphires tends to be quite good and inexpensive so craftsmanship need not be a major factor on the stone. 0.25 carat sapphires can be pretty cheap in the right context, and for studs an inexpensive finding would be appropriate.
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Nov 30, 2016 17:53
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Far too soft I'm afraid. 8 and up is probably your best bet--save andalusite for less wear-intensive use or be ready to replace periodically. So sapphire, spinel, chrysoberyl (including alexandrite), inclusion-free beryl (to avoid fracturing problems), moissanite (if you don't mind a synthetic) are probably your best options. That kind of red/green pleochroism is hard to match at higher hardness though. Alexandrite or color change sapphire could give a similar look in some lighting but can be hard to find a deal on (though I did manage to hook my cousin up with a nice alexandrite for his proposal at a reasonable price, so the deals do sometimes appear).
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Dec 18, 2016 23:01
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I'm not a real expert on this but I can give you a surface-level rundown. Heat treatment in rubies goes back to the classical era, when stones would be put under a large bonfire kept very hot by strong winds. That is a relatively low-temperature treatment, 700-1300c, and it can drive off purplish tones in some stones. I did it once (using a kiln) on a non gem-quality stone and it did yield a much purer pink color from an initially purplish, lower-saturation stone. This low-temp treatment doesn't tend to cause rutile inclusions to break down within the stone and like many lower-temperature heat treatments it doesn't leave a lot of really obvious signs that it's been done. It is even sometimes still done by hand near the mines--you'll have a little room with rubies in a fire and one or two guys with long straws spending hours just blowing on it to keep it hot. See for instance https://www.gia.edu/gia-news-research-low-temperature-heat-treatment-mozambique-ruby . The GIA describes heat treatment of ruby as essentially ubiquituous: https://www.gia.edu/gia-faq-heat-treatment-ruby Modern heat treatment of sapphires is much hotter, and can go up to about 2kish or so for longer periods of time. That's a very different animal--it causes things like the reabsorption of rutile silk into the lattice of the crystal, which can improve color and clarity. If you're after a delightfully thorough and technical breakdown the GIA put out a nice paper that breaks a lot of it down in a very readable way (WARNING: PDF link) Just in general, don't be too trusting of what a jeweler who you don't know tells you about gem treatments--you don't have to know a lot about gems to become a jeweler and many of them are woefully (or perhaps willfully) uninformed. It takes a fair amount of work to find a jeweler who really knows their stuff. Lots of undisclosed lead glass-filled stones hit the market that way, for instance.
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Dec 30, 2016 01:03
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Second stone is definitely windowed, which is not that atypical for valuable stones being cut for weight.
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Dec 30, 2016 03:21
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My dad picked up a piece of the Rwandan material at last year's show and I've been hearing a lot about it off and on since. It's definitely very attractive material! Hopefully there will be some available at slightly less than the "curated-for-hobby-faceter" price he had to pay last time.
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Dec 30, 2016 16:37
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Xun: Don't use a 100 grit for faceting. It ends up being a bit like whacking your stone with a rock, and it can cause subsurface damage that will make life harder later on. I don't facet yet but I've had some real headaches from that while doing basic flat polishing. Arkanomen: "Yellow apatite surrounding pink tourm" No, that's tourmaline on tourmaline (ie, a watermelon tourmaline). If sufficiently clean for faceting, Pala mountain tourmalines do command a bit of a premium (and all tourmaline rough has gotten pretty darned pricey). The specimen grade pieces also have some value since again it's a classic locale and they're not quite as plentiful as Brazilian or Afghan specimens. Prices for rough vary all over the place but I'd think the neighborhood is tens of dollars per gram for good facet material (I don't think I'm seeing too much here but I'll leave that judgment to others). Variable prices for crystals suitable for being sliced and polished, which also produces nice gemstones. Specimens are variable, see what they go for on eBay I guess, since that's probably one of your better options for moving them. The aquamarines don't look too promising--color is nice but included aquamarine is very plentiful. Basically they are neat specimens for locale value but that's about it. Oceanview kunzites tend to have deeper stable colors than some Afghan material (particularly since much of the inexpensive Afghan material has often had its manganese's oxidation state bumped up past where it's comfortable with some gamma rays) and again have a nice 'name brand' locale. Triphane isn't really very valuable for cutting no matter where it's from unless it's really big and really nicely colored (spodumene is also awful to facet thanks to some oddball properties and easy cleavage)--that said, the etched crystals are quite attractive and have some value as specimens or for setting as-is. Some of this shows up on eBay with regularity. Afghan material in facet grade is usually around 1/g unless something has changed recently, and since stability isn't an issue with triphane and it's more plentiful the Oceanview material's premium isn't as great. By the way, if you haven't put them under a compact fluorescent light, do it! Triphane goes from "eh..." to "EH!" when you take it from any other light source to fluorescent light. Also, a UV light because they tend to be exceptionally fluorescent, and sometimes even phosphorescent. Scarodactyl fucked around with this message at 10:32 on Jan 12, 2017 |
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Jan 12, 2017 10:18
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I'd note that if you go to the Himalaya mine and pay for their bags of pegmatite dirt (not cheap) you have a very good chance of getting high quality material. I have had a lot of luck with those over the years, definitely got more than my money's worth.
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Jan 12, 2017 20:55
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It looks like topaz but I don't want to sound too certain from a photo identification. Topaz has perfect basal cleavage, just rotate the stone around in your hand and look for a directional flash. Natural pale blue topaz isn't really very rare though it's often described as such. Nevertheless there is no reason at all to cut colorless topaz so I'd definitely plan on saving as much blue as you can. Just be sure to avoid that cleavage plane and you should be fine. I've been finding some great stuff here at Tucson! Here are some assorted pictures: http://imgur.com/a/WDuGA
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Jan 29, 2017 06:30
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Here are a few more Tucson photos if anyone's interested: http://imgur.com/a/eLpbO http://imgur.com/a/ZXMCR http://imgur.com/a/UBZVE
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Feb 1, 2017 06:17
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littlebluellama posted:Two more questions about topaz: It does resemble chatoyance a bit but it's all on the surface of the stone from flat polished faces. Internal cleavage is fairly common too but if it's a cutting-grade piece it's probably been selected to be clean, and internal cleavages are usually very visible. If you really need to orient the cleavage plane that way it shouldn't be a major issue, the 9 degrees is just to make sure you don't end up having any facets where you're trying to polish the cleavage plane (which is possible but a huge pain). Topaz isn't too likely to cleave during cutting if you don't do anything ridiculous. Goodness: very nice! I think I'm seeing welo opals, a tsavorite crystal, a nice (Jeffrey's Quarry?) peach grossular, a red garnet of some description and a nice assortment of tourmalines (is the red one Russian?). Not sure about the center peachy stone, the black and white crystal to teh side or the faceted stones (unless they're Be-sapphire?)
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Feb 5, 2017 07:11
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It's possible to be allergic to nickel or less commonly copper, both of which often feature in some alloys including white gold. I have a cousin who is allergic to nickel, or at least thinks she is.
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Feb 10, 2017 02:16
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goodness posted:Another guy is quoting 3-800 for the same material, if anyone wants one let me know before the end of today! They won't be priced under 200 for much longer Love 'em, but post-tucson is a hard time for purchases of ye fine mineral specimenes. Where are they from, if you don't mind me asking? I've seen nice ones from Afghanistan, Maine and Brazil but they always seem to have a very squat crystal form.
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Feb 11, 2017 23:42
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I love that tsavorite! Getting nice crystals is always hard given how they usually form. I've been cutting a bunch of cabs this week!   I got a nice selection of Moroccan agates at Tucson this year. There is a lot of variety in these guys--the pink banded ones are all from one piece. The large one has a thick calcite rim and a calcite core.  Some chrysoprase (Australian material from Tucson) and pink chalcedony (Texas Springs, NV limb cast material).   This is some neat Ethiopian aquamarine I picked up at Tucson--it has a beautiful silvery sheen down the C-axis.  Cat's eye aquamarine doesn't always show up well in photos but it's quite bright and mobile in person.  Gem silica; the center and left are Mexican cut from the same piece, and the rightmost piece is trimmed from a piece of Needles Blue from California, an unusual rhyolite mixture that sometimes has seams of gem silica mixed in. Scarodactyl fucked around with this message at 07:27 on Feb 27, 2017 |
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Feb 27, 2017 06:59
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There are lots and lots of undisclosed synthetic amethysts on the market--it's estimated anywhere between 60-95% of amethysts in jewelry stores. If that matters a lot to you you'd want source your stone from someone who cut it themselves from rough material that showed natural crystal faces (important because lots of rough sold to cutters is also undisclosed synthetics, sold as completely broken pieces to remove the obviously unnatural surfaces). The plus side to that would be that sourcing directly from a US cutter will let you pick out the specific stone you want, and since most US-based cutters use high precision cutting techniques (as opposed to cheap jamb peg cutting which is typical of mass-produced jewelry) you'll get a better stone too. The downside is that you'll pay more, but it's still amethyst so you're not in the diamond ballpark at all even with US cutting. The other major downside, though, is that quartz is only hardness 7. If it is worn daily the stone is going to get scratched up sooner or later, and it will have to be replaced. Again, since it is a less expensive stone that isn't necessarily a big deal but it needs to be taken into consideration. If she is careful with her rings it could last a long time but if she's hard on them it will probably go pretty quickly. There are some purple alternatives that are harder (sapphire or spinel) but they're going to be a lot more expensive, especially if you're looking for that awesome rich amethyst purple.
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Apr 18, 2017 22:30
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I like it! Looks like you did a great job. Citrine?
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Jun 13, 2017 23:29
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Neat! I imagine that you're already loaded down with rough, but if you'd like to take on another quartz I have some cool deep purple Nigerian amethyst with red hematite needles that I could send you a piece of. I think it will cut up nicely.
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Jun 14, 2017 01:22
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Not exactly--sphene is most notable for its extremely high dispersion (which is the ability of a material to split white light into its component colors). That said, it's very true that really intense green sphenes that are dead clean do seem to show off more red flashes than other colors which may have something to do with the weird complexities of red and green color perception which also contribute to color change gems. Unfortunately the videos aren't loading for me but that is some of my favorite material, really incredible stuff.
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Jun 23, 2017 09:31
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littlebluellama posted:I also had some stones I was told were sapphires, and while they were obviously "enjoy the novelty of saying you have a sapphire" quality sapphires, I was curious to see what was inside. They each had some sort of chatoyance/star. Cabbing is very fun and addictive, but the rough accumulates even faster than facet rough and it takes up more space too.
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Sep 10, 2017 06:34
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Do it. It is really fun and sometimes you can get good stuff along the way too. Don't worry about losing cred with rock hounds, most of us are just excited to know someone else is interested.
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Sep 11, 2017 00:39
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littlebluellama posted:Thanks! I love the idea of being able to make something nice out of any stone. Being in NC, there's lots of quartz and other stones in the ground, and I have joined a local gemstone and mineral club. I am hoping to go on one of their field trips this year to a quarry. I know they've found fossils and some interesting minerals in the past. Oh cool! NC is a great rock state. Have you been to any of the gem shows? The season is sort of over at this point but we have some pretty good ones. I'm in Raleigh and have a lot of cabbing rough--I'd be happy to send you some if you drop me a pm.
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Sep 11, 2017 00:45
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Oh yeah, we've definitely crossed paths then. If you've been to that show and hung out with some of them you will probably not be wanting for rough for a while. We have about 4 shows a year in that location, though the organizer just dropped the summer shows and they might not get picked up again. One thing to note about Hiddenite is that as I understand it they do salt that creek (or perhaps a previous owner), though your finds look like native material.
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Sep 12, 2017 04:59
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It kind of depends what type you're wanting to buy and in what price range. Personally, I'd suggest getting an Ethiopian stone because the prices are still fairly reasonable and you can get a wide range of patterns and base colors with remarkably good fire. The one downside is that they can absorb water if soaked (which can change fire and clarity until they dry out) so they require some care that way--on the other hand they are generally tougher than opal from other locales and don't have problems with long term stability regardless of the humidity of the environment they are kept in.
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Oct 7, 2017 22:35
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Doublets and triplets are not necessarily low quality, though one needs to be aware of them when buying. Some localities (like Spencer, Idaho) tend to produce opals with the color in thin bands, so this method is used to best show them off. Some of these can be really remarkable gems in their own right, and there are some advantages to having a harder clear cap over the opal (though an improperly made doublet or triplet can separate over time of course).
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Oct 8, 2017 06:50
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They are likely Australian (picture would help). If they have been fine so far they should be fine. Opals are a bit individual, from find to find and stone to stone. Nevada stones have some percent of stable material (10~%) while the rest crazes if not kept under water after being removed from the ground. There is one deposit in Australia that famously produced stones that were fine for like 2 years and would then start crazing. That isn't typical but some do apparently need to maintain a certain level of humidity. I haven't dealt much with these myself though, and the risks may well be exaggerated on stones that have proven themselves stable.
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Oct 8, 2017 19:41
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Digital calipers are cheap and good. I never use analog ones anymore.
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Oct 31, 2017 18:48
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Claes Oldenburger posted:Cut a Montana sapphire last week, 1.855ct and definitely one of the nicest pears I've done! I'm also through the roof at material return...got 47% out. I don't think I'll be beating that for a while haha Edit: Also, I got a new (to me) gem microscope! I've been having fun taking photos through the ocular and using helicon for focus stacking. Image dump:  Canadian hypersthene up close (70x). It appears it gets its trademark silvery sheen from platy metallic/irridescent inclusions, maybe exsolved hematite or ferrosilite.  Hard to photograph but kinda cool, dumortierine crystals in quartz. In person it is an intense blue but the microscope light is fairly yellow.  Hematite needles in rough amethyst from Nigeria with a classic nail-like crystal form. This one turned out a lot cooler than it should have. https://www.youtube.com/watch?v=qSvCWI9HXUA And a video of a mobile methane bubble inside fluorescent petroleum in a negative crystal inside a Pakistani quartz crystal (the herkimer-like ones). Scarodactyl fucked around with this message at 03:06 on Nov 3, 2017 |
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Nov 3, 2017 02:45
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